Method for bending tubes of fiber and similar material



Sept. 13, 1932. I REPLQGLE 1,877,629

METHOD FOR BENDING TUBES OF FIBER AND SIMILAR MATERIAL Filed Feb. 17,1930 Patented Sept. 13, 1932 UNITED STATES PATENT. OFFI DANIEL BENSONREPLOGLE, OF BERKELEY, CALIFORNIA, ASSIGNOR TO THE COMMERCE GUARDIANTRUST 80SAVINGS BANK, TOLEDQ'OHIO; TRUSTEE METHOD FOR BENDING TUBES FFIBER AND SIMILAR MATERIAL Application filed February 17, 1930. SerialNo. 429,188.- 7

The invention relates to a .method for bending tubes constructedof'hygroscopic material such as vulcanized fiber, hard paper tubes, ortubes composed of other cellulose or fibrous material.

conveyed to the winding mandrel by anysuitable form of conveying means.As a. result of this operation, there is formed uponthe' mandrel a tubehaving awall which is substantially homogeneous. lVhen the windmgoperation is completed, the tube itself is moist and it is thenordinarily subjected to a drying operation by which the moisture isremoved.

The present invention relates to an improved method of bending suchfibrous tubes after the forming mandrel has been removed. This may beaccomplished before the wet pulp of which the tube is composed ispermitted to dry, or if it is dried the tube may be moistened so as tocondition it for'the bending operation, for it is a prerequisite thatthe tube shall be in a condition to bend, and in a moist condition theybend best. A moist paper or fibertube is easily collapsible since thewalls thereof under these conditions possess little strength orresistance.

One of the problems which presents itself r in the bending of such tubesis to prevent the malformation of the tube and to maintain thecircularity of the tube in cross section. I

have solved this problem by causing a yielding outward pressure to beexerted uniformly against the interior of a. moist tube during thebending operation, by means of gas pressure within the tube, and thenremoving the moisture from the tube while it is still subsure ispreferably maintained within the'tube during and after the bendingoperation, and this is preferably accomplished by sealing thIsJ tube gastight and applying heat to the tu e.'

According to the preferred embodiment of becomes moist and flexible.This flexibility i may of course be obtained. by employing a tube whichhas just been formed from the web or pulp and which has not beenpermitted to dry. .The essential feature,in any event, I

is to obtain the desired flexibility of the fibrous material of whichthe tube 'is. oom-' posed. Whenjthis flexibility has been obtained, thetube is inserteds-in a bending matrix and closed gas tightQ Heat is thenapplied to expand theii'airwithin the tube I and also to generate steamfromthe moisture contained within the tube walls. 'Suflicient heat isapplied to produce a pressure which will prevent collapsing of the'wallsof the tube .7 during the bending operation. Preferably the heat shouldbeuniformly applied to the outside of thetube, both above and below, andin this manner substantially uniform temperatures inside and out of thetube are maintained. The preferable mode of supplying heat is by meansofgasburners which 7 may be very accurately regulated to produce thedesired degree of pressure within the tube. V 1

} According to the preferred embodiment of the lnvention a number oftubes'may be bent at one time and in a single matrix, and in such caseit is desirable that the gas burners be prof I vided with branches aboveand below the tubes, and corresponding in number with the number oftubes.v A single control device may be employed for regulating thesupply of gas to all the branches.

1 When the gas pressure has' thusbeen obtained within the tube'or'tubes, the bending forms or matrices and kept gas tight until the ihardening of thetubes is completed. This setting or hardening; operationis preferably.

accomplished by a continued supplyof heat,

' which performsthe dual operation of'drying the tubes and maintainingthe internal gas dust and the like.

" ing bent;

pressure during such drying and heating operation.

The advantage of gas pressure for maintaining the circularity of thetubes over other means which have been employed for similar purposes isself-evident, namely the uniformity of pressure throughout the, tube,thus avoiding marring or ridging at any portion and providing a smoothinterior or exterior surface. -Moreover, aperfect control of thepressure may be had where gas isused as the expanding medium byregulation of the heat supplied, the same heat serving both for dryingand for maintaining pressure within the tu e.

While the gas pressure alone is sufiicient to perform the desiredoperation, nevertheless it is sometimes desirable to fill the tube withfine granular material such as moist sand, saw- It is notessential thatthe sand be moist, although this is preferable.

Such granular material assists in maintaining V thecircularity of thetube, particularly prior to the time that the gas pressure is sufficientto prevent collapsing. Where moist granular materlalis used, suchmoistureproduces steam on heating of the tube, which steam producespressure to assist in maintalmng the circularity. If desired, wherealready fixed tubes are i to be bent, such fiber tubes may be firstfilled V with sand or granular material to insure the maintaining ofcircularity, and then while so filled may be soaked in water to obtainthe de sired flexibility. Obviously when so filled there is no danger ofthe tubes collapsingbefore being placed in the bending matrices.

The bending opera-tion may be desirably performedin an apparatus setforth in the accompanyingidrawing, in which Figure 1 is a top plan viewof the bending apparatus especially designed for bending gas filledtubes and for heating the gas during the bending and subsequent dryingof the tubes. in order to maintain the proper degree of pressure withinthe tubes;

Figure 2 is a longitudinal sectional view of the apparatus, the sectionbeing taken through one of the tubes, certain parts being shown inelevation, this view showing the relation of parts when the tubes are inplace withinthe forms, and just before the bending operation; 7 j o IFigure-3 is aview similar to Fig. 2 showing theparts of the device-whenthe tubes are be- Figure 4 is a detail vertical sectional view showing ameans forheating the tubes, and

Fig. 5 is a detail of one of the extension plates attached to the lowerforms.

As shown,'the bending device consists of bed member. 10, and anupperpress member ll-pivotally connectedto the bed member by means of thehinge 12. The bed member carries the lower halves 18 of a plurality of-"tube forms, herein shown as three in number,

tubes are closed air tight by means of gaskets 16'which are held inplace by caps 17, which in turn abut against projections 18 on the lowerportion of the form. The caps 17 serve to protect the ends of the tubeagainst injury or marring during the bending operation. To eachof thelower forms is pivoted an exprevent marring of the tube at that end ofthe tube form, as would obviously be the case if no such means wereprovided. In order to maintain each of the tubes gas tight, springpressed closure members 20, of rubber or like material, are provided atthe ends of the tubes opposite the gaskets 16. These closure mem bersare carried by threaded rods 21 extending through a bar 22, which iscarried-by a lever 23 secured to one ofthe pivoted shields .19. Springs24: react between the bar 22 an the closure -members 20. v In order toprevent collapsing-of the'moist tension shield 19, thepurpose of whichis to fibertubes,heat is applied, which, expands the air withintheclosed tubes and generates steam from the moisture carried by the tubes.

To supply the necessary heat, gas burners25 and 26 above and below thetube formsare provided. Sufiicient pressure will be gener ated withinthe tubes by this heating operation to prevent collapsing-of the tubesas the upper form members are lowered to the position shown in Fig. 3,by means of an operating handle 27 or other operating means, and theform may be secured in this lowered position by means of a latch member28, provided with a notch 29, which coacts with a pin 30 upon theoperating handle 27. As the tubes are bent the extension shields 19 arerotated about their pivots 31' and prevent marring of the tubes at theends of the lower tube forms 13. As the shields arerotated, the rod 23carried by the central space, swings upwardly, carrying with it the bar22 and the closure members 20, which swing in the same-arc as the tubesthe bent form. The drying operation will be assisted by'the applicationof heat from the burners, 25 and 26. The gas pressure is maintainedwithin the tubes until they have hardened sufficiently to preventcollapsing. It will be noted that accurate control of the temperatureand pressure within the tubes may be had at. all times by regulating thethemselves, and in this manner the gas tight flame from the gas burners,a valve 32 being provided for this pur ose. It is to be further notedthat uniform eating at the top and bottom of the tubes is obtained bymeans of V the upper and lower series of burners 25 and V 26. Both upperand lower burners are branched and their number corresponds to the 7number of the tubes to be bent, so that the te1nperatures and pressureswill be equalized for all of the tubes undergoing the bending operation.The upper set of burners 26 is connected to the source of supply byflexible members 33, whereby the burners 26 are readily moved upwardlyand downwardly with the upper hinged member 14 of the matrix. Thisarrangement is intimately connected with the improved process in that itpermits heat to be applied to the top of the tube to supply thenecessary pressure within the tube before the bending operation takesplace, as clearly indicated in Fig. 2. hen theupper member 14 is loweredto the position shown in Fig. 3, the burner members 26 are likewisecarried downwardly so as to remain in close proximity to the bent tubeand maintain the desired gas pressure uniformly within the tubes durinthe heating operation.

aving thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

1. A method of forming a fixed bent fiber tube which comprisessufficiently moistening the tube to render it flexible, closing the tubegas tight, heating the closed tube sufficiently to generate gas pressurewithin the tube sulficientto maintain the circularity of the tube duringbending, bending said tube while maintaining said gas pressure, anddrying the gas tight closed bent tube to cause it to set by continuedapplication of heat, thereby ing stress and simultaneously confining theoutside of the tube to prevent radially outward movement in anydirection and obstructing the inside against radially inward movement inany direction by confining a fluid within the tube.

In testimony whereof I aflix signature.

DANIEL BENSON REPLOGLE.

continuing the internal gas pressure during l the setting of the tube.

2. A method of bending and drying a moist fiber tube composed ofcellulose pulp, which comprises closing the flexible tube gas tight,heating the closed tube sufliciently to generate gas pressure within thetube sufiicient to maintain the circularity of the tube during bending,bending said tube while maintaining said gas pressure, and drying thegas tight closed bent tube to cause it to set by continued applicationof heat, thereby continuing the internal gas pressure during the setting of the tube.

3. A method such as herein described, which comprises bending a straightmoist tube into the desired curvature while causing yielding outwardfluid pressure to be exerted uniformly against the internal surface ofsuch tube by heating and thus expanding the fluid therein, and thenremoving the moisture from said tube while it is subjected to suchpressure.

4. A method of bending a moist fiber tube which comprises subjecting thetube to bend-

